Therefore we focus on the Pauli observables whose expectation values are (comparatively) large in absolute value.
When two Pauli observables \(P_1\)  and \(P_2\)  anti-commute, the expectation values of \(P_1\)  and \(P_2\)  cannot both be large in absolute value.
Hence, it is often the case that these remaining observables can be sorted into a collection of just a few sets, where operators in each set are mutually commuting.
Various sorting strategies are known [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}.
Once such a commuting set is identified, all the operators in the set can be simultaneously measured using just a single copy of \(\rho \) ,
